<template>
  <div>

    <div class="goods">
      <div class="menu-wrapper">
        <ul>
          <!--current-->
          <li class="menu-item" v-for="(good, index) in goods" :key="index"
              :class="{current: index===currentIndex}" @click="clickMenuItem(index)"> <!--计算index等不等于当前的currentIndex，如果等于那么就为true-->
            <span class="text bottom-border-1px">
              <img class="icon" :src="good.icon" v-if="good.icon">
              {{good.name}}
            </span>
          </li>
        </ul>
      </div>

      <div class="foods-wrapper">
        <ul ref="foodsUl">
          <li class="food-list-hook" v-for="(good, index) in goods" :key="index">
            <h1 class="title">{{good.name}}</h1>
            <ul>
              <li class="food-item bottom-border-1px" v-for="(food, index) in good.foods"
                  :key="index" @click="showFood(food)">
                <div class="icon">
                  <img width="57" height="57" :src="food.icon">
                </div>
                <div class="content">
                  <h2 class="name">{{food.name}}</h2>
                  <p class="desc">{{food.description}}</p>
                  <div class="extra">
                    <span class="count">月售{{food.sellCount}}份</span>
                    <span>好评率{{food.rating}}%</span>
                  </div>
                  <div class="price">
                    <span class="now">￥{{food.price}}</span>
                    <span class="old" v-if="food.oldPrice">￥{{food.oldPrice}}</span>
                  </div>
                  <div class="cartcontrol-wrapper">
                      <CartControl :food="food"/>
                  </div>
                </div>
              </li>
            </ul>
          </li>
        </ul>
      </div>
       <ShopCart/>
    </div>
       <Food :food="food" ref="food"/>
  </div>
</template>


<script>
  import BScorll from 'better-scroll'  //创建滚动元素
  import {mapState} from 'vuex'
  import CartControl from '../../../components/CartControl/CartControl.vue'
  import Food from '../../../components/Food/Food.vue'
  import ShopCart from '../../../components/ShopCart/ShopCart.vue'

  export default {
    data(){
       return {
         scrollY: 0,//右侧滑动的Y轴坐标(滑动过程时实时变化)
         tops:[], //所有右侧分类的li的top组成的数组 (列表第一次显示后就不再变化)
         food: {}, //需要显示的food
       }
    },
     mounted(){
       this.$store.dispatch('getShopGoods',() => { //callback数据更新之后会执行
          this.$nextTick(() => {  //列表数据更新显示后立即执行

            this._initScroll()
            this._initTops()
          })

       })

     },
    computed:{
       ...mapState(['goods']),

      //计算得到当前分类的下标
      currentIndex (){
         //得到相关的条件数据
         const {scrollY, tops} = this
        //根据条件计算得到的结果
         const index = tops.findIndex((top, index) => {
            //scrollY>=当前top && scrollY<下一个top
           return scrollY>=top && scrollY<tops[index+1]
         })
        //返回结果
         return index
      }
    },

    methods: {
      //初始化滚动条
      _initScroll(){
        //列表显示之后才能显示出滑动块
        new BScorll('.menu-wrapper',{
             click:true
        })
         this.foodsScroll = new BScorll('.foods-wrapper',{
          probeType: 2 ,//  惯性的滑动不会触发 但是比1要灵敏
             click:true
        })

        //给右侧列表绑定scroll监听
        this.foodsScroll.on('scroll',({x, y})=>{
          console.log(x,y)
          this.scrollY = Math.abs(y)  //绝对值
        })
        //给右侧绑定一个结束滚动的监听
        this.foodsScroll.on('scrollEnd',({x, y})=>{
          console.log('scrollEnd',x,y)
          this.scrollY = Math.abs(y)
        })
      },

      _initTops(){
        //1.初始化tops
        const tops = []
        let top = 0
        tops.push(top)
        //2.收集
        //找到所有分类的li
        const lis = this.$refs.foodsUl.getElementsByClassName('food-list-hook')  //精确的定位li的地址
        Array.prototype.slice.call(lis).forEach(li => { //把假数组给转化为真的数组然后遍历
          top += li.clientHeight
          tops.push(top)
        })
        //3.更新数据
        this.tops = tops
        console.log(tops)
      },

      clickMenuItem(index){
           //使用右侧列表滑动到对应的位置
           //得到目标位置的scrollY
           const scrollY = -this.tops[index]  //定位index所标记的tops里的位置
           //立即更新scrollY(点击的分类项成为当前的分类)
           this.scrollY = scrollY
           //平滑滚动右侧列表
           this.foodsScroll.scrollTo(0, scrollY, 300)
      },

      //显示更新的food
      showFood(food){
        //设置food
        this.food = food
        // 显示food组件(在调用子组件对象的方法)
        this.$refs.food.toggleShow()
      }
    },

    components:{
        CartControl,
        Food,
        ShopCart
    }

  }
</script>

<style lang="stylus" rel="stylesheet/stylus">
  @import "../../../common/stylus/mixins.styl"
  .goods
    display: flex
    position: absolute
    top: 195px
    bottom: 46px
    width: 100%
    background: #fff;
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
      width: 80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
        width: 56px
        padding: 0 12px
        line-height: 14px
        &.current
          position: relative
          z-index: 10
          margin-top: -1px
          background: #fff
          color: $green
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
        .text
          display: table-cell
          width: 56px
          vertical-align: middle
          bottom-border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        color: rgb(147, 153, 159)
        background: #f3f5f7
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        bottom-border-1px(rgba(7, 17, 27, 0.1))
        &:last-child
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            line-height: 12px
            margin-bottom: 8px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 8px
              font-size: 14px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
              color: rgb(147, 153, 159)
          .cartcontrol-wrapper
            position: absolute
            right: 0
            bottom: 12px


</style>
